Sunday, December 15, 2013

Equatorial Minnesota

Today is December 15, 2013. It has reached perhaps a robust 7 °F outside (or -14 °C), and several inches of snow cover the ground here in the Twin Cities. In short, Minnesota is not a place you associate with the Equator, tropical warmth, balmy seashores, and the like. It wasn't always like this, though. Jump in your favorite time machine and go back 20,000 years ago. Hopefully, it's smart enough to compensate for the fact that glacial ice covers the land and doesn't try to materialize within it. If you can get the door open, you'll see that the weather can always be worse. Now, kick the slush off of your boots (you did come prepared, didn't you?) and spin the dial to 1.1 billion years ago. It should be somewhat warmer: provided you sprung for the expensive automated chrono-telometry package and so are not drifting in deep space, you should now be viewing an impressive rift valley, complete with volcanoes.

But I promised the tropics, didn't I? Head home now, collect your swim gear, get your time machine somewhere along the bluffs in St. Paul or Minneapolis, and plug in 454 million years ago. Southeastern Minnesota is near the margin of a shallow continental sea a few degrees south of the Equator. It's a sunny day with the trade winds blowing across the water. There are no sharks to worry about, but there are a number of squid-like animals with long straight shells (I probably should have mentioned that earlier). The seafloor teems with branching things, small clam-like shells, plant-like sea lilies, snails, and crawling things that look kind of like pillbugs.

Or perhaps you'd like the beach, or at least something with fewer squid-like things and crawly things? Take the time machine a few million years before our last stop and navigate to the coast. You'll find the purest beach sand you can imagine. There aren't any palm trees for shade, but at least the sun is not quite as powerful as it will become, and it is unlikely that any of the invertebrates had invented CFCs and such, so the UV rays should be more manageable. Also, you'll have that beach all to yourself.

Or maybe you say "The heck with that! I can go to a beach any time I want. I've got a time machine – I want to see dinosaurs!" Why not start at sometime between 100 and 95 million years ago? Depending on your exact geography, you'll end up on a coastal plain or above (hopefully) another shallow sea. There are dinosaurs wandering the land, although we don't know much about them yet, and creatures like coiled ammonites and sharks in the sea, with marine-adapted relatives of crocodiles along the coast.

Of course, nobody's actually got a working time machine, and anyone who did would probably be busy fighting the temptation to commit historical crimes, committing historical crimes, or doing things that would erase the universe, so it's probably a good thing. However, it is possible to observe the records of these times and places, probably a lot closer than you'd expect. Passing Dayton's Bluff? There's that beach, beneath the rocks from the shallow equatorial sea. Stopping by St. Anthony Falls? You're looking at a remnant of a waterfall system that formed at the end of the last ice age. Taking in the fall foliage in the St. Croix River Valley? Part of the "basement" is the old rift. These are what Equatorial Minnesota is about. I plan to share information about the geology and paleontology of the state, from rock formations to types of fossils to notable localities to the human history. Because my professional background is strongly linked to the National Park Service, I'll also sometimes discuss the geology and paleontology of Park Service units. Of course, my personal interest starts with Mesozoic animals, particularly dinosaurs, so they'll also get the occasional spotlight. Finally, I reserve the right to occasionally toss in something else. I hope you find this blog to be enjoyable and informative!
Post-glacial river meets tropical coast

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